【作者】 于莉；

【导师】 张建新；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2008， 硕士

【摘要】 大米是我国人民的重要食品,大米的储藏是关乎国家食品安全的重大问题。本文针对我国大米储藏过程中的主要问题,以天津小站稻大米越选4#为试材,采用自发气调与人工气调相结合的处理方法,重点研究大米气调包装、含水量、温度等因素对大米储藏过程中真菌微生物和品质变化的影响,提出了大米最适保鲜方法,同时研究了不同膜材料对大米的保鲜效果和大米中黄曲霉毒素B1高效液相测定方法。主要研究结果如下:(1)大米在不同气调包装条件下储藏73d时编织袋包装的大米脂肪酸增加了131%,真空包装的增加了36.4%;编织袋储藏的大米中还原糖含量138d时与充气和真空包装相比分别增加47.6%,37.5%,自然缺氧储藏的大米中还原糖含量比充气和真空包装分别增加59.5%,48.4%;编织袋和自然密闭储藏138d大米的粘度值降到3.5 mp·s,而充气和真空包装的为6.8mp·s。可见采用真空包装储藏大米保鲜效果较好。(2)游离脂肪酸、还原糖品质指标的变化速率与大米初始含水量呈正相关,水分含量、脂肪酸、还原糖与储藏时间呈正相关;从大米感官评价来看低水分含量的大米与原是样品无明显差别;低水分含量的大米带菌率也是最低为20%;不同水分条件的大米的保质效果差异明显,低水分的大米品质劣变慢。(3)高温储藏条件下,大米经6个月的储藏,脂肪酸值是初始值的9倍,还原糖为初始值的3.82倍;低温和室温下,大米品质指标变化幅度很小;脂肪酸的变化速率与温度正相关;在低温条件下大米两种气调包装方式储藏的品质指标来看,真空包装优于自发气调包装。(4)小包装大米储藏保鲜实验经过夏储藏易感染虫子、蛾子;复合袋包装的大米经过33d的储藏后脂肪酸值增加了21.3%,198d时还原糖增加了223%。从6种保鲜膜包装大米的品质指标来看,粮食防霉保鲜膜(厚度:0.08)的保鲜效果最好,不仅延缓了大米的陈化,而且在一定程度上起到了防霉保鲜作用。(5)导致大米变质的优势菌是霉菌;大米中AFB1方法的回归方程为y=4.09e+006x+2.25e+002,相关系数R=0.999957,线性关系良好;AFB1平均回收率为89.67%,平均变异系数为5.60%;大米样品AFB1的检出率67.24%,超过国家限量标准率为3.45%。更多还原

【Abstract】 Rice is the primary food of our country. Rice storage is the important question of our coutry food safety. Solving the mainly questions of rice storage in the paper, using the milled rice of Yuexuan 4# as material and adopting the methods of modify atmosphere and control atmosphere, it mainly research that the effects of the number of mildew and quality changes of rice storage during the atomsphere packages, water contents, temperature in the rice preservation, and gain the fresh storage method, in the same time also research the effects of rice storage using different films and put forward the method of AFB1 of aging rice using HPLC.The mainly results as follow:(1) The rice fatty acid of the bianzhi packages was increased by 131% in 73 days storage, and the rice fatty acid of the vacuum packages was increased by 36.4% in 135 days storage during different atmosphere packages. The rice reducing sugar during bianzhi packages was increased to 47.6%, 37.5% in compare with the controlled atmosphere packages and the vacuum packages in 138 days. The rice viscidity of the bianzhi packages and the modify atomosphere packages was declined by 3.5 mp·s, but the rice viscidity of the vacuum packages and the controlled atmosphere packages was 6.8mp·s after 138 days storage. The vacuum pack of rice storage was the best.(2) The ratios of fatty acid and reducing sugar of rice were relation to the original water content of rice. The water contents, fatty acid and reducing sugar were relation to the storage time of rice. The rice of the lower water contents was similar to the original rice sample on the sensory character.The ratio of rice mildew of the lower water contents was the lowest,20%. The different water contents of rice storage had different quality changes. The lower water content of rice quality was the slower of quality changes.(3)In the high temperature the rice fatty acid after six monthes storage was nine times of the original value.The rice reducing sugar was 3.82 times of the original value. The quality changes of rice became slow in the low temperature and room temperature. The vacuum pack was prior to the modify atmosphere pack by the trend of the quality changes of rice storage.(4) The rice of the small package had insects and moths by the summer storage. The rice fatty acid was increased to 21.3% after 33 days storage and the redusing sugar was increased by 223% after 198 days storage. The rice packing by food special plastic film(thickness:0.08mm) was best, slower to the rice aging, and preventing the mould from the rice quality changes by the six kind films packing.(5) The mildew was the predominance of the degenerative rice. The regress equation of AFB1 of rice was y=4.09e+006x+2.25e+002, correlate coefficient R=0.999957, the relation of linearity was good. The average recovery of AFB1was 89.67%, and average variation was 5.60%. The ratio of AFB1 of rice samples was 67.24%, the ratio of overrun the country standard was 3.45%.更多还原